Production of turbine blades



July 24, 1956 J. JAMESON 2,755,604

PRODUCTION OF TURBINE BLADES Filed Feb. 4, 1953 2 Sheets-Sheet 1 July 24, 1956 J. L. JAM ESON 2,755,604

PRODUCTION OF TURBINE BLADES Filed Feb. 4, 1955 2 Sheets-Sheet 2 ATTOR/VEXJ United States Patent PRODUCTION OF TURBINE BLADES Joseph Lambert Jameson, Betchworth, England Application February 4, 1953, Serial No. 335,101

Claims priority, application Great Britain February 4, 1952 9 Claims. (Cl. 51-141) This invention relates to method and apparatus for the production of turbine and like blades (hereinafter referred to as turbine blades) and especially those having a high length/width ratio with a correspondingly large change in angle along their length, i. c. with a correspondingly large degree of twist from one end to the other: such blades are employed in, for instance, the lower-pressure end of the gas compressors of pilotless missiles and in aero-gas turbines.

The method of producing turbine blades with which the invention is concerned comprises registering a blade work-piece to a preformed die surface having (in obverse) the shape to which the surface of the blade is to be finished and in causing relative movement between the registered workpiece and die and an abrasive band disposed between the juxtaposed blade and die surfaces so that, by pressing the blade and die towards one another, the abrasive surface of the band causes the form of the die surface to be reproduced on the blade surface.

It is of course clear that this method relies on the flexibility of the abrasive band which is required to conform to the surface of the die: the method is entirely satisfactory for most blade forms which have a length/width ratio in which the degree of twist of the blade does not require excessive flexing of the band: when however the method is applied to the production of blades forming the concern of this invention, the large twist over the length of the blade would subject the band to execssive flexure and the band would therefore have such a short working life as to render the method impracticable: such blades would also be diflicult to finish by reason of the relatively long length of the blade and its thinness.

Now according to this invention the surface of a blade having a high length/width ratio is formed by the method which consists in registering the blade and the die to one another, in moving between the blade and the die an abrasive band having a width which is only a fraction of the length of the blade and in moving the blade and die on the one hand and the band (at least in that part where it passes between the blade and die) on the other hand relatively in the direction of the length of the blade.

The relative movement can be effected progressively (i. e. continuously) along the length of a blade or alternatively it can be effected in a number of stages in each of which a sectional length of the blade is substantially completed. In this alternative case, the die, the blade and the band will be held registered against movement in the direction of length of the blade, and in each stage the die and blade would be urged towards one another to effect the finishing operation on the corresponding sectional length of the blade.

In some cases, the blade, having been operated on in this way in a number of stages, could be given a final clean by causing the blade and die holder on the one hand and the band on the other hand to sweep continuously along the entire length of the blade.

It would in general be preferred to hold the band against movement along the length of the blade and to move the die and the blade holder in that direction, although of course, the converse arrangement could equally well be employed.

By this invention the band is required at any one time to flex only to the limited extent required by a fraction of the total twist of the blade. It is also preferred to arrange for the die and blade on the one hand and the band on the other hand to be moved relatively in a plane transverse to the length of the blade, the movement being such that the angle of approach of the band is adjusted to suit the particular angle of twist of that part of the blade upon which it is operating so as thereby still further to reduce flexure of the band: thus the band could approach the blade at an angle such as represents the mean of the twist angle of the blade at points representative of the width of the band.

Thus the band is not subjected at any time to excessive flexure and in addition the blade can be satisfactorily dealt with despite its length and thinness as at any time only part of its total length is being operated upon.

The twist of the blade can be regarded as occurring about an axis which extends lengthwise of the blade and the adjustment of the blade and die on the one hand and of the band on the other hand in the transverse plane could be effected by angular movement about such an axis.

The invention is illustrated in the accompanying drawings in which Fig. 1 is a perspective view of a typical turbine blade of the form with which the invention is concerned and Fig. 2. is an end elevation of such a blade.

Figs. 3-5 are diagrammatic views showing the steps in operation of two forms of the invention, Fig. 6 is a perspective View of a construction embodying one form of the invention, Fig. 7 is a detail perspective view thereof and Fig. 8 is a side elevation of a further detail employed in that machine.

Referring firstly to Figs. 1 and 2, the turbine blade shown has a high ratio of length L to width W and a large change in the angle of twist 0 as shown in Fig. 2.

A very eflicient way of finishing turbine blades is described in the pending application No. 261,178 and this involves the use of a die having a shape which corresponds (in obverse) to the shape to be reproduced on the blade and also an endless abrasive band which is moved between the surface of the die and the face of a blade which is registered to the die. The abrasive face of the band is presented to the surface of the blade workpiece and its non-abrasive surface is backed by the die so that by moving the die and workpiece towards one another, the abrasive face of the band finishes the blade forming surface of the workpiece to the requisite form.

In Figs. 37 the die is shown at 1, the blade or workpiece at 2 and the abrasive band at 3.

It will be clear that if an abrasive band 3 of a width approximating to the length of a blade were used to finish the blade along its length, the band would have to flex by an amount approximating to the angle 0 and where the angle 0 is large the corresponding flexure of the band 3 would also be large and in the result the band would have a short working life.

In accordance with one aspect of the invention this difl'iculty is avoided in using an abrasive band 3 which is a part only of the length L of the blade, the total length of the blade being dealt with by moving either the band die and. blade are moved: towards one another and. are:

moved (while maintaining; their registration in the length.- wisesense. of, the blade, so that the; finishing operation on. the blade. 2 is efiiected. progressively along; its-length.

bythe' fractional width abrasive: banda. It: could. be. anrangedithat the die; and blade. couldbe. moved backwardsand forwards: along-:thebrasive': band.- and=the feed: (i... e. the? reduction in the distance separatingthe. surfaces: of the die. and; the: blade); could b'e-progressively reduced; to. thelimit required. In Fig. 3 the feed: is. indicated. by the arrow 201,. the longitudinal movement by the arrows y.

It. is however preferred to operateshy-the method shown:

in Figs. 4 and 5. in these figures; the die: 1-. and blade 2 are heldagainst' longitudinal movement while a sectional length of the blade 3- is finished,:this being illustrated in Fig-.. 4 where. the fractional lengthlr of the. blade isxbeing treated by moving by moving the die. 1 and. blade. 2 to.- wardsone. another as indicated by the feed arrow A61. The die and blade. are then separated andtare then moved to gether longitudinally as indicated by the longitudinal arrow yr. This action presents another fractional length 12 of the blade 2 for similar treatment by the band 3 as shown in Fig. 5, the feed for this fractional length 12. being denoted by the arrow :02.

In the particular case shown; the; blade; 2 is finished in two stagesalthough obviously thenumber. of stages can be. greater than two as may be found necessary. Whatever be the number of stages-it is preferable asis indicated in Fig. 5 to return the parts to their original position while the die and blade are maintained in their: position of feed. This movement is indicated by the arrow ya in Fig. 5- and by this movement the band 3 is caused to clean the entire surface of the blade 2. as a final finishing operation.

A part of a machine for carrying out the, preferred operation described with reference to Figs; 4 and 5 is shown in Fig. 6. In this figure the die 1 and a holder 4 toreceive a blade 2' are both carried by a support 5 which is itself slidable on guide bars 6 carried by a. support 5 carried by the main frame 7 of the machine. The abrasive band 3 is driven by being passedv between the surface of a driven drum 8 and a flexible non-abrasive band 9 which itself passes over pulleys 1'0, 11, 12 of which one is driven. The band 3 is thus trapped. between the surface of the drum 8 and theband 9 and. so i positively driven, the band passing thence over a guide roller 13, thence through what may be termed a drag box 14 hereinafter referred to, then between the die 1 and the blade 2, and thence via a guide roller 15 to the drum 8.

In the construction shown, the blade holder 4 is. caused to be lowered to urge the blade 2: against the abrasive band 3 where that band passes over the die 1:. the mechanism for effecting the raising and lowering of the blade.

holder 4 can conveniently be that describedin the pending application No- 261,178 and further description in this specification is therefore believed. to be unnecessary except to point out that. the blade holder 4 would constitute the blade holder 90 shown. in the pending application Serial No. 261,168. In this case the die 1 is fixed against vertical movement but of courseto carry the? operation described with reference to Figs. 3-5 into etfect'the support 5 (and hence the blade holder 4 and the: die 1) is moved on the slide bars at the. appropriate time to" effect thelongitudinal movement y or yr, ya.

This longitudinal movement can be effected in any convenient manner as by an hydraulic ram and cylinder arrangement controlled by valves operated in timed relationship with the feed movements x, x1, 1:2.

The invention also contemplates the step of adjusting the angle of approach or departure (or both) of the abrasive band 3 to or from the die. 1 so as to enable the band to be adjusted to suit the angle of twist at the particular part of the blade operated on by the band as it passes along the length of the blade.

For this purpose and as applied to controlling the band as it approaches the die, the band 3 passes between rollers 16, 17, 13, 19 in the. drag. box 14.to. or from the space between the die 1' and the. blade 2. This drag box is arranged to be raised and lowered as the support 5 is moved longitudinally to-present the various parts lengthwise of the blade to the band and the movement of the drag box is chosen so that the endless band is caused to pass between the blade and the; die atwhat maybe: average twist over that part of the blade being. operated upon. Toobtain that result, the drag box 14. is carried at the. outer end of a frame 20 (see Figs. 6 and 7), whicltis. carried by arms 21 pivoted at 22 on the fixed frame 7. The frame 20 is thus free to rock and so=to raise and lower the drag box 14, and the. drag box is fitted with a stylus 23 which passesinto a control track 24- extending. in the sense of the longitudinalmovement y. This-control track is carried by the support 5. anditis set atsuch an angle. that as the support 5 is, moved longitudinally i. c. to. produce the movement y or 1, ya, the drag box 14 is raised and lowered to suit the angle of the. blade.

As. is shown in Figures 6 and. 8, the rollers 16 and 18 in the drag box 14 are subjected. to. the. frictional drag effect of a spring 26 which can be regulated bya screw 2'11: by this means the band3 isv maintained. flat. and is prevented from buckling transversely when. the. blade 2' and die 1 are moved longitudinally while they are. pressed together as for the movement in Figure 3 or of the movement ya, in Figure. 4. It may also be set so that when the bladelis moved awayfrom the die 1,, the band 3. is caused to run with suflicient slackness to prevent its becoming taut over the die when (as. is. shown) it is of concave form to finish the. convex face of a blade and in this way to allow the. blade into the concavity. The roller 15 over which the'band3 passes from the die, may also be. carried by a bracket 28 which is pivoted at its rear end. about a vertical pivot so that it can be swungin step with thelongitudinal movement referred to to maintain the belt running true.

While it is preferred as shown to use. an endless. abrasive band 3 which is constantly moved in the one. direction it would of course be possible to move. the band backwards. and forwards.

What I claim is:

1. Finishing the surface of turbine or like blades by the method which consists in registering. the blade to a die having a surface preformed to correspond in obverse to that to be produced on the blade, in disposingbetween the die and the blade at art anglethereto an abrasiveband' which has its abrasive face opposed to the. blade and which has a. width which is a fraction only of the. length of the blade surface, in urging the blade and the die to.-

wards one another, in relatively moving, the registered die and blade and the band lengthwise of the band to. cause the abrasive of the band to: reproduce on the blade the form of the die where it backs the'band, in relatively moving the registered, die and blade and the bandin the direction of the length of the blade torenable the narrow band to finish the surface length of the blade, and. in varying the angle between the band and the die and the blade while relatively moving the dieand the'bl'ade and the band in the direction of the length of the blade.

2. Finishing the surface of turbine or like blades by the method which consists in registering theblade' tor a die having a surface preformed to correspond in obverse to that to be produced on the blade, in disposing between the die and the blade at an angle thereto an abrasive band which has its abrasive face opposed to the blade and which has a width which is a friction only of the length of the blade surface, in urging the blade and the die towards one another, in relatively moving the registered die and blade and the band lengthwise of the band to cause the abrasive of the band to reproduce on the blade the form of the die where it backs the band, in progressively relatively moving the registered die and blade and the band in the direction of the length of the blade to enable the narrow band to finish the surface length of the blade, and in varying the angle between the band and the die and the blade while relatively moving the die and the blade and the band in the direction of the length of the blade.

3. Finishing the surface of turbine or like blades by the method which consists in registering the blade to a die having a surface preformed to correspond in obverse to that to be produced on the blade, in disposing between the die and the blade at an angle thereto an abrasive band which has its abrasive face opposed to the blade and which has a width which is a friction only of the length of the blade surface, in relatively moving the registered blade and die and the band in the length of the band, in relatively moving the registered blade and die, and the band lengthwise of the blade in a number of steps to register the narrow band with the different lengthwise portions of the blade, in varying the angle between the band and the die and the blade in each stage, and in urging the blade and the die towards one another in each step whereby the band reproduces on the blade the form of the section of the die where it backs the band in each step.

4. Finishing the surface of turbine or like blades by the method which consists in registering the blade to a die having a surface preformed to correspond in obverse to that to be produced on the blade, in disposing between the die and the blade at an angle thereto an abrasive band which has its abrasive face opposed to the blade and which has a width which is a fraction only of the length of the blade surface, in relatively moving the registered blade and die and the band to one another in a first direction lengthwise of the band and in a second direction lengthwise of the blade, and in effecting said movement in said second direction in a number of stages in which the narrow band is registered to the different sectional lengths of the blade, in varying the angle between the band and the blade and the die in each stage and in urging the blade and the die towards one another in each stage.

5. For finishing the surface of a turbine or like blade, apparatus comprising a die holder and a blade holder which are registered to one another, the die holder receiving a die having a preformed surface and the blade holder receiving a blade having its surface registered to the die,

means to move the die and blade holder towards and away from one another in successive stages, means training between the holders and transversely thereto an abrasive band having a width which is a fraction only of the length of the blade, means to move the holders and the band relatively lengthwise of the band, means operating to move the holders and the band relatively lengthwise of the blade at each stage whereby the narrow band is caused to operate over the full length of the blade, and means operating finally to move the holders and the band relatively lengthwise of and over the full length of the blade while the holders are urged towards one another.

6. For finishing the surfaces of turbine or like blades, apparatus comprising a die holder, a blade holder, means registering the holders to one another, means training an abrasive band between the holders and transversely to the length of a blade in its holder, the band having a width which is a fraction of the length of the blade, means to move the holders and the band relatively lengthwise of the blade, means to urge the holders towards one another whereby the abrasive band is backed by a section of the die and reproduces over the width of the band the sectional shape on the blade, means to move the holders and 6 the band relatively lengthwise of the blade to cause the narrow band to traverse the die and the blade, and means to move the holders and the band training means relatively to adjust the angle of the band relative to the die at the different positions of the band lengthwise of the die.

7. For finishing the surface of a turbine or like blade, apparatus comprising a die holder and a blade holder which are registered to oneanother, the die holder receiving a die having a preformed surface and the blade holder receiving a blade having its surface registered to the die, means to move the die and blade holder towards and away from one another, means to train an abrasive band between the holders and transversely thereto, the band having a width which is a fraction only of the length of a blade, means to move the holders and the band relatively lengthwise of the band, means to move the holders and the band relatively lengthwise of the blade to cause the narrow band to operate over the full length of the blade, and means to move the band training means and the die holder relatively to one another to adjust the angle of the band relative to the die at the different positions lengthwise of the die.

8. For finishing the surface of a turbine or like blade, apparatus comprising a die holder and a blade holder which are registered to one another, the die holder receiving a die having a preformed surface and the blade holder receiving a blade having its surface registered to the die, means to move the die and blade holder towards and away from one another in successive stages, means training between the holders and transversely thereto an abrasive band having a width which is a fraction only of the length of the blade, means to move the holders and the band relatively lengthwise of the band, means operating to move the holders and the band relatively lengthwise of the blade at each stage whereby the narrow band is caused to operate over the full length of the blade, means operating finally to move the holders and the band relatively lengthwise of and over the full length of the blade while the holders are urged towards one another, and means to move the holders and the band training means relatively to adjust the angle of the band relative to the die at the different positions of the band lengthwise of the die.

9. For finishing the surface of a turbine or like blade, apparatus comprising a die holder and a blade holder which are registered to one another, the die holder receiving a die having a preformed surface and the blade holder receiving a blade having its surface registered to the die, means to move the die and blade holder towards and away from one another in successive stages, means training between the holders and transversely thereto an endless abrasive band having a width which is a fraction only of the length of the blade, means for driving the band, means to move the holders and the band relatively lengthwise of the band, means operating to move the holders and the band relatively lengthwise of the blade at each stage whereby the narrow band is caused to operate over the full length of the blade, means operating finally to move the holders and the band relatively lengthwise of and over the full length of the blade while the holders are urged towards one another, and means to move the holders and the band training means relatively to adjust the angle of the band relative to the die at the different positions of the band lengthwise of the die.

References Cited in the file of this patent UNITED STATES PATENTS 1,288,908 Johnson Dec. 24, 1918 1,415,785 Brown May 9, 1922 1,974,806 Curtis et al. Sept. 25, 1934 2,426,764 Czarnecki Sept. 2, 1947 2,431,822 Murray Dec. 2, 1947 2,453,972 Clave et al. Nov. 16, 1948 2,479,506 Payton Aug. 16, 1949 2,575,656 Coe et al Nov. 20, 1951 2,587,603 Czarnecki Mar. 4, 1952 

